Screw-making machine



i (No Model.) 2 Sheets-Sheet. 1.

D. P. JOHNSTON. Y SCREW MAKING MACHINE. No. 514,007. Patented Feb. 6, 1894.

2 t e e h S .W. e e h B 2 N 0 T S N H 0 J R D (.No Model.)

sonnw MAKING MA-GHINE. No. 514,007.

Patented Feb. 6, 1894.

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UNITED STATES PATENT OFFICE.

DAVID P. JOHNSTON, OF CHICAGO, ILLINOIS.

SCREW-MAKING MACHINE.

SPECIFICATION forming part of Letters Patent No. 514,007, dated February 6, 1894.

Application filed April 1, 1 892.

To all whom it may concern.-

Be it known that I, DAVID P. JOHNSTON, a citizen of the United States, residing at Ohicago, Cook county, Illinois, have invented certain new and useful Improvements in Screw-Making Machines, of which the following is a specification.

The object of my invention is to provide means for adjusting and regulatingthe position of the cutting mechanism so as to determine the depth of the groove cut in the screw blank, to form the point of the screw, and to return the parts to their normal position; and theinvention consists in the features, details of construction, and combinations hereinafter described and claimed.

In the drawings, Figure l is a plan View of the cutting tool applied to a screw blank, together with means for adjusting such tool, the means for holding the blank not being shown,inasmuch as they form nopart of this invention; Fig. 2 a cross section on line 2 of Fig. 1, looking in the direction of the arrow, and Fig. 3 a perspective view of a cam plate or former, the last two figures being on an enlarged scale.

The means for holding and revolving the screw blank may be made in any desired form, and since they form no part of my invention will not need to be shown.

'Attached to any suitable stand or frame work, is a pair of. ears A, which afford bearings for the operating parts of my invention,

. as about to be described. Supported upon a shaft B, journaled in these cars, is a rocking frame 0, preferably, though not essentially, of the form shown in the drawings, wherein it is provided with two downwardly projecting lugs or ears 0', O, a set screw 0, and'a cam plate or former D, shown more particularly in Fig. 3. Pivoted at a suitable point in this frame is a hook E, the point e whereof is adapted to be engaged by a cam wheel F, revolving upon a suitable shaft f. This hook is also provided with a downwardly projecting lug e for the purpose hereinafter to be described.

Passing through thelugs O, O", and abutting against the lug e is a bolt or rod G, screw threaded, to engage with threads formed on the interior of the lug C", the lug 6' being normally kept in engagement with the end Serial No. 427,385. (No model.)

of this rod by means of a spring G. This rod is held in any desired position by means of the set screw 0. Above the shaft B, arod His supported in the ears A, and also a bearing A attached to the frame work of the machine. This rod carries the holder 1, in which is placed the screw cutting tool 2', which is adapted to act upon the screw blank J. A spring I normally tends to draw this tool holder and rod in the direction of the ears A, as will be apparent from an inspection of the drawings.

Rigidly secured to the rod H is an arm H, resting normally upon the upper face of the cam-plate D. The spring 1' acts as already stated, to move this rod, together with the tool and arm, in one direction; to move it in theother I provide a cam wheel or eccentric K, which engages with the end of the rod, as shown more particularly in Fig. 1. v

The mechanism operates in the following manner, supposing the parts to be in their normal position and the tool brought to the point upon the blank where it is to commence its work. The blank is revolved, as is also the cam wheel K, by any suitable mechanism,

(not shown) and as the wheel revolves until one of the teeth f engages with the hook E, this depresses the tool and brings it into position to cut the groove, and as the cam revolves it will gradually move the rod H, and therefore the tool holder and tool along a horizontal line, thus cutting a spiral groove around the blank. When the tooth passes the point e, the latter will fall into one of the recesses of the cam, and the spring I will return the parts to their downward position, when the above operation is repeated.

The parts should be so adjusted that the arm H will reach the beveled or inclined face (1 on the cam plate D, at the time when it is desired to form the tapering point of the screw. As the arm rises up this incline it will rock the rod H toward the right, (Fig. 1) depressing the tool to the desired amount, thereby cutting more deeply into the blank and forming the point.

Just as the screw is finished the cam wheel F will have revolved until the hook comes to the plane face f when the tool will not be depressed to cut and the finished screw can be removed and another blank inserted.

Various parts of this device are obviously adjustable, since the rod G can be screwed out through the lug O", and held in any position, through the set screw 0, thereby adjusting the position of the tool, while the arm 11' can be adjusted at various points along the rod H, as may be desired. By this means I provide a simple and efficient device for regulating the action of the screw cutting mechanism, which is automatically adjusted to cut the thread along the shank and at the point of the screw, and to be brought back automatically to its normal position upon the completion of the screw, and while I have shown more or less precise forms I do not wish to unduly limit myself to them, but contemplate all suitable or desirable changes that may be made without departing from the spirit ofmy invention.

I am aware of Patent No. 256,546, issued April 18, 1882,to A. S. Cook, for a wood screw machine. That machine differs from mine in various particulars-among others in location and operation of theadjustingscrew M. This screw being situated at the top of the machine, it is necessary for the attendant to rise and reach over the machinery in order to operate the screw, which is both objectionable and dangerous; while in my machine, the screw, entering from the side and acting-upon the hook at the point beyond the pivot, can be operated without rising and without the attendant difficulty.

I claim- 1. In a screw-making machine, the combination of a frame engaging with the rod carrying the tool holder and pivoted substantially along its central axis,a hook pivoted in the frame, a cam wheel engaging the hook, a rod passing horizontally through the frame and engaging with the hook, and means for adjusting this rod, substantially as described.

2. In a screw-making machine, the combi-' nation of a frame pivoted substantially along its central axis and provided with downwardly depending ears, a rod passing horizontally through such ears and extending out at the front of the machine, a hook pivoted in such frame and provided with a downwardly extending lug engaging with such rod, a cam wheel engaging with the hook, and means for adjusting the rod, substantially as described.

8. In a screw making machine, the combination of a frame pivotally supported substantially along its center line, a hook pivoted in such frame and provided with a depending lug, an adjusting rod extending horizontally beneath the frame and contacting with the lug on the hook at a point forward of the pivot, and a spring for maintaining the contact between thelug and rod, substantially as described. j

4. In a screw-making machine, the combination of a frame engaging with the rod carrying the tool holder and pivoted substantially along its central axis, a former secured to the upper surface of said frame and at the front of the machine, an arm secured to said rod and normally resting upon the face of said former, and means for moving said rod forward, substantially as described.

DAVID P. JOHNSTON.

W'i tnesses:

EPHRAIM BANNING, SAMUEL E. HIBBEN. 

